The present invention relates to an image reproducing method and apparatus, more particularly, to image processing technology in an open system corresponding to a plurality of kinds of input devices and output devices.
An image reproducing system for obtaining a reproduced image by subjecting the image data fetched in through an input device such as a scanner, an image reading device or the like to predetermined image processing such as gradation adjustment, sharpness correction and so on, and supplying the image data thus subjected to the image processing to an output device such as a display, a printer or the like has been put to various uses.
In such an image reproducing system as described above, the input device such as an image reading device or the like, an image processing unit for performing the predetermined image processing and the output device for outputting the reproduced image are normally made to one-to-one correspond to one another.
With the development of computers, workstations and the like in recent years, use is increasingly made of an open system corresponding to a plurality of kinds of input devices and/or output devices: for example, a system capable of reproducing images by making a workstation subject the image data read by an image reading device to image processing, and outputting the image data thus processed to a printer, a CRT and the like; and a system capable of outputting reproduced images by using an image reading device and a digital camera for fetching in one sheet of original image and subjecting the image data thus obtained to image processing individually in a workstation.
In the open system like this, it is required to obtain the same reproduced image stably when the same original image is processed, irrespective of the kind of the input/output device.
In the printing field wherein the progress of DTP (Desk Top Publishing) is conspicuous, for example, printing is carried out through the steps of causing an image reading device to photoelectrically read an original image, a workstation to process the original image data that has been read, an image recording device using photosensitive materials to output a reproduced image as a proof to be corrected, and then of preparing a printing plate after the termination of proof corrections.
Therefore, the reproduced image after the proof corrections is required to properly conform to a printed image. It is also required for the same proof to be stably output even when the original reading device and the image recording device for outputting a proof are replaced.
Notwithstanding, the characteristics of input and output devices usually vary with the kind of the device, irrespective of the printing field, and in the open system in which the plurality of kinds of input and output devices are dealt with, there is a problem arising from the fact that the color/density, image structure and the like of the reproduced image are varied by the input and output devices, even if an image is reproduced using the same original image.
In order to solve this problem, ICC (International Color Consortium) proposes ICC Profile Format Specification.
This specification is aimed to output the same image from one original image without relying on the characteristics of input and output devices by having a conversion table for converting image data on R, G and B into image data on an XYZ colorimetric system of CIE (Commission International de l'Eclairage) and a 3.times.3 matrix as device profiles as far as, for example, image data on red (R), green (G) and blue (B) is concerned; by processing the image data on R, G and B fetched in through the input device to convert the RGB image data to the image data on the XYZ colorimetric system; by subjecting the XYZ image data to various kinds of image processing; and ultimately converting the XYZ image data to image data (e.g., image data on R, G and B, and C, M, Y and K) corresponding to the output device.
By the use of this method disclosed in the above specification, it becomes possible to output the same color/density image from the same original image without relying on the kind of input/output device in such an open system.
Even in the method above, however, image structure dependent on sharpness and the like still tends to vary with the kind of input/output devices and when a device is changed in the open system, images having the same image structure cannot be output from one original image with stability. In consequence, the operator's feeling will have to be relied on under the present circumstances as far as the image structure of the reproduced image is concerned.